Autonomous Sensor Fish to Support Advanced Hydropower Development

ABSTRACT

An improved sensor fish with robust design and enhanced measurement capabilities. This sensor fish contains sensors for acceleration, rotation, magnetic field intensity, pressure, and temperature. A low-power microcontroller collects data from the sensors and stores up to 5 minutes of data on a non-volatile flash memory. A rechargeable battery supplies power to the sensor fish. A recovery system helps locating sensor fish. The package, when ready for use is nearly neutrally buoyant and thus mimics the behavior of an actual fish.

RELATED PATENT DATA

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 16/056,185 which was filed Aug. 6, 2018, which is acontinuation of and claims priority to U.S. patent application Ser. No.14/871,761, which was filed on Sep. 30, 2015, now U.S. Pat. No.10,067,112 issued Sep. 4, 2018, the entirety of each of which isincorporated herein by reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY-SPONSOREDRESEARCH AND DEVELOPMENT

This invention was made with Government support under ContractDE-AC0576RL01830 awarded by the U.S. Department of Energy. TheGovernment has certain rights in the invention.

BACKGROUND OF THE INVENTION Field of the Invention

The invention generally relates to environmental sensors and moreparticularly to sensors utilized in hydro dams or other hydraulicstructures to assess the forces encountered by fish passing through suchdams and other structures and characterize complex flow field.

Background Information

Fish passing through hydroturbines or other hydraulic structures may beinjured or killed when they are exposed to the severe hydraulicconditions found therein. Such conditions could include rapid andextreme pressure changes, shear stress and turbulence, strike by runnerblades and cavitation. In building new dams and as existing turbinesnear the end of their operational life and are set to be replaced, newdesigns for runners and other portions of the turbine system are beingconsidered. As part of this effort, in the Pacific Northwest andelsewhere, improved survival rates and reduced injury rates for fishpassing through turbines are being considered as design parameters. Tocreate these designs, data is needed to understand the environmentthrough which the fish were required to pass.

Studies using live fish are useful for the evaluation of dams'biological performance, but are limited in that they cannot determinethe specific hydraulic conditions or physical stresses experienced bythe fish, the locations where deleterious conditions occur, or thespecific causes of the biological response. To overcome this deficiency,various other sensor devices have been developed. These devices can bereleased independently or concurrently with live fish directly intooperating turbines or other passage routes as a means of measuringhydraulic conditions such as pressure, acceleration, and rotation actingon a body in situ during downstream passage. These early devices wereoriginally designed for the large Kaplan turbines in the Columbia Riverbasin and were used by the U.S. Army Corps of Engineers, whocollaborated with the U.S. Department of Energy for its development, forvirtually all of their post-construction structural and operations fishpassage evaluations at main-stem Columbia River dams. Correlationmetrics between these early sensor measurements and live fish injurieswere also developed by conducting concurrent releases in turbulent shearflows under controlled laboratory conditions.

While useful in their time, these types of devices have tended to lackthe sufficient robustness required to survive the rapidly changing andextreme conditions within the testing sites. In addition the speed atwhich conditions change made most of these sensors less useful becausethey were not able to acquire information in rapid fashion so as to givethe true account of the significant changes that took place in thebodies of these fish as they passed through these environments. Thesize, functional limitations and problems with deployment and recovery,availability, and cost of these prior art devices have limited its usebeyond the main stem Columbia River and its original application. Asnewer designs for turbines, dams, and pumping stations provide new andunknown conditions that the existing sensor devices cannot tolerate andwhich may not adequately reflect and report the conditions to which itis subjected.

Desirable devices overcome some of these limitations; they can berobust, cost accessible, as well as provide rapid data acquisition andbe more widely deployable and be operable in more severe hydraulicconditions including but not limited to high-head dams with Francisturbines and pump storage facilities. Additionally, desirable devicescan have outputs that can be more readily read and understood than theexisting processes for the old devices.

The present disclosure provides sensor fish with more capabilities thatcan accelerate conventional hydropower development by shorteningschedules and decreasing costs for validation of performance claims toregulators, and by providing feedback to design engineers about many ofthe hydro-turbine designs and environmental settings being considered toincrease power generation. The sensor fish and utilization thereof can,lower the procurement and deployment costs which can be important forincreasing the accessibility and acceptance of this sensing technology.

Additional advantages and novel features of the new sensor fish andmethods will be set forth as follows and will be readily apparent fromthe descriptions and demonstrations set forth herein. Accordingly, thefollowing descriptions of the present fish and methods should be seen asillustrative of the fish and methods and not as limiting in any way.

SUMMARY

Pacific Northwest National Laboratory has completed a two-year projectto develop a “sensor fish” that addresses the limitations of the priorart devices. The result and improved or GEN 2 sensor fish providesimproved robustness of the design and enhanced measurement capabilitiesusing innovative sensors and circuitry; reduced future costs and a modelthat is capable of deployment in numerous areas wherein such items werenot previously deployable. This sensor fish contains sensors foracceleration, rotation, magnetic field intensity, pressure, andtemperature. A low-power microcontroller collects data from the sensorsand stores up to 5 minutes of data on a non-volatile flash memory. Arechargeable battery supplies power to the sensor fish. A recoverysystem helps locating sensor fish. The package, when ready for use isnearly neutrally buoyant and thus mimics the behavior of an actual fish.

To operate the sensor fish, the user activates the microcontroller usinga magnet, and then drops the device in the water (typically, on theupstream side of a dam). The microcontroller waits for a preselected andpreprogrammed period of time and then samples data from each sensor atup to 8,092 Hz. Data collection continues for a preselected programmableperiod of time configurable time, or until the internal memory is full.The microcontroller then activates the recovery mechanism on each end ofthe enclosure to release weights for ballast causing the fish to rise tothe surface and provide a sensing alarm (e.g. radio frequencytransmission and strobe lights) to facilitate the identification andlocation of the device. The recovery mechanism consists of aspring-loaded weight tied down with a piece of fishing line that loopsover a nichrome wire. The microcontroller briefly applies a largecurrent through the nichrome wire, which heats up the wire, severs thefishing line, and releases the weight on each end. The weights drop andthe package rises to the surface. The microcontroller then activatesintegrated LED flashers along with a radio frequency (RF) beacon sousers can locate the package. Applying the magnet again turns off thebeacons. After collection, from the water, the sensor fish is thenconfigured for placement into a docking station where in the datacollected during the event can be down loaded into a larger system foranalysis. The docking station plugs into the flex circuit board on oneend to recharge the battery and download the sensor data. After the datais downloaded the flash memory is then typically erased. New weights andfishing line (connectors) are installed and the sensor fish is ready forthe next deployment.

The purpose of the foregoing summary is to assist the United StatesPatent and Trademark Office and the general public, especially thescientists, engineers, and practitioners in the art who are not familiarwith patent or legal terms or phraseology, to determine quickly from acursory inspection the nature and essence of the technical disclosure ofthe application. This summary can be relied upon to support the claimedinvention; however the summary is not intended to be limiting as to thescope of the claims in any way.

Various advantages and novel features of the present disclosure aredescribed herein and will become further readily apparent to thoseskilled in this art from the following detailed description. In thepreceding and following descriptions only the preferred embodiments ofthe invention are shown and described, by way of illustration of thebest mode contemplated for carrying out the invention. As will berealized, the invention is capable of modification in various respectswithout departing from the invention. Accordingly, the drawings anddescription of the preferred embodiment set forth hereafter are to beregarded as illustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective side views of a first preferredembodiment of the present invention

FIG. 2 is a block diagram of the electrically connected components ofthe present invention.

FIGS. 3A and 3B are detailed views of the recovery mechanism of thepresent invention.

FIG. 4 is a perspective view of another embodiment of the deployment ofthe present invention.

FIG. 5 is a perspective view of another embodiment of the presentinvention.

DESCRIPTION

This disclosure is submitted in furtherance of the constitutionalpurposes of the U.S. Patent Laws “to promote the progress of science anduseful arts” (Article 1, Section 8). The following description includesthe preferred best mode of one embodiment of the present invention. Itwill be clear from this disclosure that the invention is not limited tothese illustrated embodiments but that the invention also includes avariety of modifications and embodiments thereto. Therefore the presentdescription should be seen as illustrative and not limiting. While theinvention is susceptible of various modifications and alternativeconstructions, it should be understood, that there is no intention tolimit the invention to the specific form disclosed, but, on thecontrary, the invention is to cover all modifications, alternativeconstructions, and equivalents falling within the spirit and scope ofthe invention as defined in the claims.

FIGS. 1-5 show a variety of embodiments of the present invention.Referring first to FIGS. 1A and 1B, views of one embodiment of thepresent invention are shown. FIGS. 1A and 1B show a “sensor fish” 2having a housing 4 that defines a body. The housing 4 is dimensioned tohave the size and density similar to those of a yearly salmon smolttypically averaging 3 to 5.25 inches (73-134 mm). In this embodiment thehousing 4 is a clear polycarbonate cylinder 24.5 mm in diameter and 89.9mm long, weighs approximately 42.1 g, when loaded with the sensors (26,18, 20, 22, and recovery mechanisms 24 and has a size and densitysimilar to those of a yearling salmon smolt. This body 4 containsthree-dimensional (3D) rotation sensors (i.e. 3-axis gyroscope) 22, 3Dlinear acceleration sensors (i.e. 3-axis accelerometers) 16, a pressuresensor 20, a temperature sensor 18, a 3D orientation sensor (i.e. 3-axismagnetometer) 6, a radio-frequency (RF) transmitter 10, a recoverymechanism 24, and a communication module. A low-power microcontroller 6collects data from the sensors and stores up to 5 minutes of data on aninternal non-volatile flash memory at a sampling frequency of 2,048 Hz(can be configured to up to 8,192 Hz). A rechargeable battery 8 suppliespower to the sensor fish. A recovery mechanism 24 makes the sensor fishpositively buoyant and float to the surface for recovery after apre-programmed time. For ease of use the housing was made of a cleardurable poly carbonate material. However in other applicationsappropriate modifications could also be made to this particular design.

The primary components were placed so that the center-of-gravity is veryclose to the geometric center of the housing 4. While these particularcomponents are described below, in additional detail it is to bedistinctly understood that the invention is not limited thereto but maybe variously alternatively configured within the scope of the inventionas defined by the claims. In the described embodiment, the primaryaccelerometer 16 (ADXL377, Analog Devices, Inc., Norwood, Mass., USA) isa chip-scale package, low power, three-axis analog component with atypical full-scale range of ±200 g per axis and a 10,000 g shocksurvival overload rating. The accelerometer 16 also has user-selectablebandwidths to suit different applications, with a range of 0.5 Hz to1300 Hz for the x-axis and y-axis (see FIGS. 1A and 1B for axisdefinition) and a range of 0.5 Hz to 1000 Hz for the z-axis. It isplaced at the center of a flex circuit board 36, which coincides withthe center of mass of the device, for the greatest accuracy.

The gyroscope 22 (ITG-3200, InvenSense, Inc., San Jose, Calif., USA) isa digital-output three-axis microelectromechanical systems componentwith a full-scale range of ±2000°/s per axis. The ITG-3200 includesthree 16-bit analog-to-digital converters, which are used to digitizethe gyroscope outputs. It includes a user-selectable internal low-passfilter bandwidth and an inter-integrated circuit (I²C) interface. Theinitial zero-rate output is ±40°/s, and the linear accelerationsensitivity is 0.1°/s·g. The gyroscope 22 also includes an embeddedtemperature sensor 18. The gyroscope 22 is mounted near the center ofthe flex circuit board 36, close to the accelerometer 16.

The eCompass module (LSM303D, STMicroelectronics, Geneva, Switzerland)integrates a three-axis digital accelerometer 16 and a three-axisdigital magnetometer 6 in the same package. The accelerometer 16 has amaximum full-scale range of up to ±16 g, and thus is not suitable forcollecting data during the most intense part of the passage (e.g.,collision with structures), but it can improve the precision of theremaining data. The magnetometer 6 has a selectable full-scale range ofup to ±12 gauss. As with the gyroscope 22, this component supports anI²C serial bus interface and has an on-board temperature sensor 18.

The pressure sensor 20 (MS5412-BM, Measurement Specialties, Inc.,Hampton, Va., USA) on the flexible board consists of a micromachinedsilicon pressure sensor 20 die mounted on a 6.2×6.4 mm ceramic carrier;it has a full-scale range of 14 bar (203 psia) with a linear range of 12bar (174 psia). The overpressure rating is 30 bar (435 psia). Thepressure sensor is of the Wheatstone bridge type with a typicalfull-scale span of 150 mV and zero offset of ±40 mV. The positive andnegative outputs connect to an instrumentation amplifier on the flexcircuit board 36. This amplifier has gain set to 12.9 and offset set to50 mV, which allows an input range of −40 to +190 mV for 0 to 12 barmeasurements.

The primary temperature sensor 18 (TC1046, Microchip Technology Inc.,Chandler, Ariz., USA) on the flexible board is also an analog componentwith linear temperature slope of 6.25 mV/° C. and a full-scale range of−40 to +125° C. The temperature sensor is mounted close to the pressuresensor 20, with the intervening space covered with heat-conductive epoxy(Omega Bond 200, OMEGA Engineering) to improve the thermal contactbetween the temperature sensor 18 and the metal enclosure of thepressure sensor 20, which comes into direct contact with the water.

Referring to FIGS. 3A and 3B, recovery mechanism 24 is depicted thatincludes a download board and a program board 40, each located at oneend of the sensor fish. The download board 40 allows users to downloadserial data from the sensor fish and recharge the battery, and theprogram board allows users to update the microcontroller firmware. Bothboards contain a nichrome wire 50 used for the recovery mechanism, whichconsists of a spring-loaded 58 weight 12 tied down with a piece offishing line that connects to an end cap 52 and loops 55 over thenichrome wire 50. A foam insert 42 can be used to provide increasedbuoyancy to the unit. In use the microcontroller 14 briefly applies alarge current to the nichrome wire 50, which heats up the wire 50,severs the fishing line 48, and releases the weight 12 on the end. Theprocess is then repeated for the opposite end of the sensor fish 2 torelease a second weight 12. Without the weights the sensor fish 2 risesto the surface. This typically begins after the first weight has beenreleased. A radio-frequency transmitter 10 and four high-intensityorange light-emitting diodes (LEDs) 26 are activated periodically sothat users can locate the device. The carrier frequency of the RF pulseis between 164 to 166 MHz for compatibility with existing receiverequipment. However, the frequency can also be set between 1 MHz to 220MHz to accommodate different receiver equipment. The LEDs 26 faceoutward to permit good visibility in most orientations, and the colorwas chosen to provide good contrast with water. For scenarios where anorange LED is not suitable other sensor fish can be manufactured usingan alternate color.

The users activate the sensor fish 2 by holding a magnet near a magneticswitch 39 located on the main flex circuit board 36. The sensor fish 2then performs a self-check to make sure that the battery voltage isabove a preset threshold and the flash memory is empty. A successfulcheck causes the status LED 26 to flash yellow indicating the start of aconfigurable data acquisition delay time; otherwise, the status LEDflashes red. After the delay time has elapsed, the sensor fish 2 startscollecting sensor data and saving it to flash memory. Once dataacquisition is complete, the status LED 26 first flashes greenindicating the start of a configurable resurface time. After theresurface time has elapsed the sensor fish 2 activates the recoverymechanism 24. Finally, the LEDs and RF transmitter are activatedperiodically until the sensor fish 2 is located and the magnetic switch39 is triggered. After data is collected and the sensor fish 2 isretrieved, it is placed into the docking station. The status LED 26 onthe sensor fish 2 is set to red, and if/when the battery is fullycharged, the battery charging indication LED 26 is set to green,otherwise, LED 26 is set to red. The sensor fish 2 then waits for serialcommands from the docking station sent by the sensor fish Communicatorsoftware. The docking station plugs into the sensor fish 2 on thedownload board 26 to recharge the battery 8 and download the sensor datavia a two-pin serial interface. The docking station uses atransistor-transistor-logic to Universal Serial Bus (TTL-to-USB)converter module to transfer the data to a personal computer. It canservice up to four sensor fish 2 simultaneously. Users interact with thesensor fish via communication software developed at Pacific NorthwestNational Laboratory (PNNL), with the serial port configured to 921.6kHz, 8 data bits, 1 start bit, 1 stop bit, and no parity. The sensorfish communicator can also be used to convert the raw binary data fileinto a comma-separated value (CSV) file with physical units, usingcalibration coefficients, and plot the resulting data. All of thesensors, including the pressure sensor 20, three-axis accelerometer 16,three-axis gyroscope 22, three-axis magnetometer 6, and temperaturesensor 18 were calibrated and evaluated individually before and afterassembly in the lab. All data analysis was conducted using MATLABprograms (The MathWorks, Inc., Natick, Mass., USA).

The electronics design of the new sensor fish 2 is shown in an overallblock diagram in FIG. 2. The design contains two main circuit boards: ananalog board for most of the sensors, and a digital board for themicrocontroller 14 and various peripherals. These two boards are stackedon top of each other, with the battery 8 in between, and mounted in themain body 4 of the device. Additional sensors are mounted onto aflexible circuit board 36 and glued into a port on the outer enclosure.A small adapter board on one end of the sensor fish 2 contains arecovery mechanism 24, serial download interface, and input to thebattery charger. This board connects to a docking station, not shown.Another adapter board on the opposite end of the device contains asecond recovery mechanism and a port for reprogramming themicrocontroller 14.

Power to the device is provided by a battery 8. In the preferredembodiment the battery 8 is a lithium polymer battery 8 with a nominalcapacity of 100 mA·h. The maximum recommended discharge current is 200mA, and the recommended recharge current is 50 mA. An integratedprotection circuit cuts off the battery on an over-discharge condition.In one embodiment the maximum continuous current consumption of thesensor fish 2 is about 70 mA when the flash memory is being erased.However, this operation is normally performed in the docking stationwith the battery charger supplying extra current. The maximum transientcurrent consumption is about 130 mA with the LED flashers 26 on. Thebattery 8 connects to the board at terminals TP1 and TP2. The positivebattery terminal is not exposed outside the sensor fish 2 to preventaccidental short circuits or current leakage while in water. The batterycharger U5 can accept up to 6.0 V, and has an output current limit setto 50 mA. The LDO regulator U6 with active high enable generates a 3.0 Vsupply for all the sensors.

The primary accelerometer 16 is a 3-axis analog component with a typicalfull-scale range of ±200 g. A 4.7 nF capacitor on the outputs sets thebandwidth of the accelerometers to 1 kHz. The outputs then drive theanalog inputs of the microcontroller 14. As the microcontroller 14oversamples the accelerometer 16 at 8.192 kHz, additional anti-aliasingfilters proved unnecessary. The accelerometer 16 is located at thecenter of the flex circuit board 36 for greatest accuracy. Other analogsensors are mounted on the flex circuit board 36. The pressure sensor 20is an analog component with a full-scale range of 14 bar (203 psia) witha linear range of 12 bar (174 psia). The overpressure rating is 30 bar,or 435 psia. A similar component is available with a full-scale range of70 bar and overpressure rating of 180 bar, but lower linearity. Thepressure sensor 20 is of the Wheatstone bridge type with a typical fullscale span of 150 mV and zero offset of ±40 mV. The positive andnegative outputs connect to instrumentation amplifier on the analogboard. This amplifier has gain set to 12.9 and offset set to 50 mV,which allows an input range of −40 to +190 mV.

The temperature sensor 18 on the flex circuit board is also an analogcomponent with a full-scale range of −40 to +125° C. As a high bandwidthis not required, the output connects directly to the microcontroller 14on the digital board. The temperature sensor 18 is mounted close to thepressure sensor 20, with the intervening space covered withheat-conductive epoxy to improve the thermal contact between thetemperature sensor 18 and metal enclosure of the pressure sensor 20,which comes in close proximity to the water. The gyroscope 22 is a3-axis digital component with a full-scale range of ±2000°/s. Theinitial zero-rate output is ±40°/s, and the linear accelerationsensitivity is 0.1°/s·g. The gyroscope 22 also includes a temperaturesensor 18. The digital I2C interface uses a separate power supply tomitigate noise. The gyroscope 22 is mounted near the center of the flexcircuit board 36, close to the accelerometer 16. The 3-axis digitalaccelerometer 16 and 3-axis digital magnetometer 6 are combined into thesame package. The accelerometer 16 has a maximum full-scale range of upto ±16 g, and thus is not suitable for collecting data during the mostintense part of the passage, but can improve the precision of theremaining data. The magnetometer 6 has a maximum full-scale range of upto ±12 gauss. As with the gyroscope 22, the component has an on-boardtemperature sensor 18 and uses a separate power supply for the digitalI2C interface. The mounting location is near one corner of the flexcircuit board 36, as alignment with the center of mass is not critical.The controller circuitry for the recovery mechanism is placed on theanalog board due to space constraints. Noise from this component is nota concern since the data collection ends before the device resurfaces.Controller first charges a capacitor bank to −30 V. Bleeder resistorsand help equalize the voltages across the series tantalum capacitors.The energy is then directed through the nichrome wires 50 viatransistors. The other ends of the nichrome wires 50 are tied to ground.The resulting large current spike immediately severs the fishing line.Note that the −30 V signal is not exposed to the environment to preventa leakage current path through the water. The battery power and sensordata enters the digital board via headers. A low quiescent current LDOregulator generates a 3.0 V supply for the microcontroller 14, and isalways active while the battery 8 is connected. A separate LDO regulatorwith active high enable provides another 3.0 V supply for the flashmemory.

A 16-bit PIC microcontroller 14 that operates the sensor fish 2. Whennot collecting data, the microcontroller 14 operates from an internallow-frequency oscillator to save power. The LDO regulators for thesensors and flash memory are turned off. The user activates the sensorfish by holding a magnet near magnetic switch 39. The digital output ofthis Hall Effect sensor drives an interrupt pin of the microcontroller14. The microcontroller 14 then turns on the LDO regulators andactivates crystal to generate a 14.7456 MHz clock. This frequency is aneven multiple of the standard 921.6 kHz baud rate used for downloadingdata. Bi-color LED 1 blinks green, yellow, or red to indicate the systemstatus. The microcontroller 14 contains a 12-bit successiveapproximation analog-to-digital converter (ADC) to digitize the sensordata. The sensor supply voltage and ground from the analog board connectto the ADC voltage reference pins 19 and 20. This configuration reducesthe effect of digital noise. Note that the ADC supply pins must beconnected to the main supply pins 39 and 40; in fact, a low-resistancepath exists between the two supplies inside the microcontroller 14.Besides the sensor data, the microcontroller 14 also measures thebattery voltage via transistor and the associated resistor divider. Inthis particular embodiment the flash memory has a capacity of 16 MB,although a pin-compatible 32 MB replacement is available. The memory isorganized into pages of 256 B; writing a full page at a time is mostefficient. The microcontroller 14 communicates with the flash memory viaSPI.

Transistors, of the analog board for example, can be used to activatethe recovery mechanism 24. The gate-source voltage on these transistorssteps from 0 to about 10 V. After the sensor fish 2 resurfaces, themicrocontroller 14 blinks four high-intensity orange LEDs 26 to thatusers can locate the device. The color was chosen to provide goodcontrast with water. The LEDs 26 face outward to permit good visibilityin most orientations. The microcontroller 14 also activates anintegrated RF beacon upon resurfacing which generates the carriersignal, and drives the antenna. The microcontroller 14 simply turns onand off to generate an RF pulse with transistor. The carrier frequencyis between 164 to 166 MHz for compatibility with existing receiverequipment. The frequency can also be set between 1 MHz to 220 MHz toaccommodate different receiver equipment when using differentcomponents. The antenna may be folded inside the housing or fed throughthe outer enclosure to form a “tail”. While the present embodiment isshown, it is to be understood that various other alternative embodimentsare contemplated within the scope of the claims of the presentapplication.

The analog and digital boards plug into two adapter boards, one locatedat each end of the sensor fish 2, which contain the nichrome wire 50used for the recovery mechanism. One board, known as the download board,allows users to download serial data from the sensor fish 2 and rechargethe battery 8. The other board, known as the program board, allows usersto update the microcontroller firmware. The docking station charges thebattery via power and ground connections on the download board, anddownloads data from the microcontroller via a two-pin serial interface.The data transfer uses RS-232 at 921.6 kHz baud rate, but with 3.0 Vlogic levels. The docking station may use a commercial TTL-to-USBconverter cable or similar circuitry to pass the data to a personalcomputer. When the sensor fish 2 is placed in the docking station, theRX signal is pulled high and wakes the microcontroller from sleep mode.Note that the RX signal is connected to two pins on the microcontroller:one for the serial communication, and the other for the dedicatedinterrupt. The analog board, digital board, download board, and flexboard are combined on the same panel to reduce fabrication costs. Eachis a four-layer board in this application. The microcontroller containsfirmware which provides the logic for operating the sensor fish 2,whereas the other modules define the interfaces to various componentswith the necessary initialization routines. Short functions areimplemented as macros to reduce the execution time. Preferably the fullversion of the MPLAB C30 compiler is required to generate optimizedcode; otherwise, the sensor fish 2 will work, but the sampling rate maynot be consistent.

Upon reset, the microcontroller 14 calls Port_Initialize to set initialvalues of all output pins. Parameters such as the data collection timeare set to default values. The startup clock source is the internal32.768 kHz oscillator. Execution then falls into Port_Wait, which placesthe microcontroller 14 in sleep mode until an interrupt occurs. Asdescribed earlier, the two interrupt sources are the magnetic switch andthe RX signal from the docking station. If the docking station pulls theRX signal high, the microcontroller 14 enters the main_downloadfunction. The status LED is set to red, the flash memory is powered on,and the external 14.7456 MHz crystal is activated. The function thenwaits for serial commands from the docking station. A complete listingof commands appears later in this section. The Uart_Update function isresponsible for processing the serial command string and decoding theassociated parameter value, if any. Any invalid characters cause theserial interface to be reset. The microcontroller 14 only exitsmain_download if the docking station sends a quit (“Q”) command and theRX signal then falls back low.

If the magnetic switch trips, the microcontroller calls main_check toensure that the battery voltage is over a preset threshold and the flashmemory is empty. A successful check causes the status LED to flashyellow for a configurable delay time; otherwise, the status LED flashesred and the microcontroller returns to the main loop. After the delaytime has elapsed, the microcontroller 14 calls main_acquire to collectsensor data. The sensors, flash memory, and 14.7456 MHz crystal are allpowered on and initialized. The function then executes a time-criticalloop to sample the sensor data. The loop consists of 24 data acquisitionsteps, or ticks. The time interval between each tick is metered byTimer2, which fires at 24.576 kHz intervals. Thus, the 24 ticks repeatat an overall rate of 1.024 kHz. However, some sensors are sampled morethan once: the analog sensors at 8.192 kHz, the gyroscope at 2.048 kHz,and the magnetometer at 1.024 kHz. The microcontroller adds four analogsamples together and saves the data at 2.048 kHz. This process, known asoversampling, reduces noise and preserves the full bandwidth of 1.024kHz.

Table 1 lists the operations performed during each tick. The ADC and twoI2C modules operate in parallel, so the microcontroller generally startsthe operations and then reads the results at the beginning of the nexttick. However, two ADC conversions are performed for each tick.

TABLE 1 Operations performed in data acquisition function. Tick ADC 12Cto gyroscope 12C to magnetometer  0 accel x + pressure start + address +write start + address + write  1 accel y + temperature command command 2 accel z + voltage start + address + read start + address + read  3accel x + pressure gyro t upper byte mag t upper byte  4 accel y +temperature gyro t lower byte mag t lower byte  5 accel z + voltage gyrox upper byte stop + start + address + write  6 accel x + pressure gyro xlower byte command  7 accel y + temperature gyro y upper byte start +address + read  8 accel z + voltage gyro y lower byte mag x upper byte 9 accel x + pressure gyro z upper byte mag x lower byte 10 accel y +temperature gyro z lower byte mag y upper byte 11 accel z + voltage stopmag y lower byte 12 accel x + pressure start + address + write mag zupper byte 13 accel y + temperature command mag z lower byte 14 accelz + voltage start + address + read stop + start + address + write 15accel x + pressure gyro t upper byte command 16 accel y + temperaturegyro t lower byte start + address + read 17 accel z + voltage gyro xupper byte accel x upper byte 18 accel x + pressure gyro x lower byteaccel x lower byte 19 accel y + temperature gyro y upper byte accel yupper byte 20 accel z + voltage gyro y lower byte accel y lower byte 21accel x + pressure gyro z upper byte accel z upper byte 22 accel y +temperature gyro z lower byte accel z lower byte 23 accel z + voltagestop stop

The main_acquire function writes sensor data to the flash module duringticks 11 and 23. This module contains an internal buffer for temporarydata storage. The function then calls Flash_Update periodically totransfer words from the internal buffer to the flash memory. After 256 Bare transferred, Flash_Update sends a page program command to write thedata into nonvolatile storage. Subsequent data values are placed in thebuffer until the flash memory is ready. Flash_Update is designed tocomplete quickly in the spare cycles available between each tick. Oncedata acquisition is complete, the microcontroller returns to low-powermode and calls main_resurface. The status LED first flashes green for aconfigurable delay time. The function then activates the boost converterand engages the recovery mechanisms, one at a time. Finally, the LED andRF beacons are activated periodically until the sensor fish 2 is locatedand the magnetic switch is tripped. The sensor fish 2 saves data inbinary format as a series of records. One record is created for eachloop of 24 ticks in the data acquisition function, which occurs every1,024 Hz. The record consists of a 2-byte header, set to 8000 hex,followed by the sensor data as 2-byte words. All values are inbig-endian format with the upper byte first. No data values are 8000hex, permitting records to be synchronized easily. Each record containstwo values from the analog sensors and gyroscope, as these sensors aresaved at 2,048 Hz, and one value from the magnetometer and secondaryaccelerometer, as these sensors are saved at 1,024 Hz. Themicrocontroller 14 outputs the binary data as described in response to a“B” command. For the “T” command, the microcontroller 14 converts each2-byte word to a signed integer and outputs the values asspace-delimited text. The header of 8000 hex is converted into a newlineto delimit consecutive data records. The sensor fish communicatorsoftware enables communication between the flash memory and a computerfor performing the data analysis. See Table 2 for example data format.

TABLE 2 Format of one Sensor Fish data record. Item Bytes header (8000hex) 2 primary accelerometer x, y, z 6 pressure 2 temperature 2 batteryvoltage 2 gyroscope temperature 2 gyroscope x, y, z 6 primaryaccelerometer x, y, z 6 pressure 2 temperature 2 battery voltage 2gyroscope temperature 2 gyroscope x, y, z 6 magnetometer temperature 2magnetometer x, y, z 6 secondary accelerometer x, y, z 6 TOTAL 56

In some embodiments the senor fish of the present design (termed AdultsSenor Fish) can be combined within a larger body to provide separatesensing for portions of a fish and to obtain data of the particularenvironmental conditions and stresses that would be placed upon a largerfish passing through such an environment. An example of such anembodiment is shown in FIGS. 4-5. As shown in FIGS. 4-5 placement of thevarious sensors within a larger fish carcass (a simulated fish shapedbody made of resilient resin) that floats within the water and mimicsthe movement of a fish as it moves through the hydraulic system. Therecovery system and weights for recovery are not always applied in theselarge body embodiments. In some deployments the fish were collected intoa pool and netted.

Adult sensor fish was applied to understand the physical conditionsadult fish experience when they pass through the Whoosh TransportConduits. The Whoosh system is an innovative adult fish passage method.Two different lengths of Whoosh Transport Conduits (40 and 250 ft) wereset up for the evaluation. The adult sensor fish successfully collectedphysical conditions data through both configurations.

A field evaluation of the new sensor fish was performed at the spillwayof Ice Harbor Dam, which is located on the Snake River, 16 riverkilometers from its confluence with the main stem of the Columbia River,in south-central Washington State. The dam is 860 m long and 30.5 m talland consists of a six-unit powerhouse, a ten-bay spillway, a navigationlock, two fish ladders, a juvenile fish bypass facility, and a removablespillway weir. The spillway is 180 m long and has 15.2 m tainter gates.Three sensor fish were released in front of Spillbay 6. During thereleases, the flow from Spillbay 6 was 8.5 kcfs (241 m³/s) and the totalspill was 41.6 kcfs (1,178 m³/s). The sensor fish were introduced intothe spill discharge flow from the spillway deck using a fishing pole anda downrigger release clip (Black Marine RC-95 downrigger release clip)at a depth of approximately 15.2 m immediately upstream of the spillopening. The sensor fish were recovered in the tailrace and data wassuccessfully recovered from all sensors for all releases.

While various preferred embodiments of the invention are shown anddescribed, it is to be distinctly understood that this invention is notlimited thereto but may be variously embodied to practice within thescope of the following claims. From the foregoing description, it willbe apparent that various changes may be made without departing from thespirit and scope of the invention as defined by the following claims.

What is claimed is:
 1. A method for collecting environmental data usinga sensor fish, the method comprising: providing a sensor fish comprisinga power source, processing circuitry, a microcontroller, and aballasting member; dispatching the sensor fish into an environment tocollect environmental data; collecting environmental data with thesensor fish using the processing circuitry; and actuating themicrocontroller to release the ballasting member to cause the sensorfish to become more buoyant.
 2. The method of claim 1 further comprisingdownloading data from the microcontroller and erasing a portion ofmemory of said microcontroller to prepare said microcontroller for asubsequent deployment.
 3. The method of claim 1 further comprising usingthe sensor fish to detect at least one parameter comprising one or moreof orientation, acceleration, rotational velocity, magnetic fieldintensity, pressure, and/or external temperature.
 4. The method of claim1 wherein the sensor fish is nearly neutrally buoyant prior to releasingthe ballasting member.
 5. The method of claim 1 further comprisingsampling data using the sensor fish at up to 8,192 Hz for a preselectedprogrammable period of time.
 6. The method of claim 1 further comprisingtriggering an alarm to facilitate identification and location of thesensor fish.
 7. The method of claim 1 furthering comprising identifyingthe sensor fish using an LED.
 8. The method of claim 1 furthercomprising identifying the sensor fish using a radio frequency (RF)beacon.
 9. The method of claim 1 further comprising selectivelyactivating or deactivating the microcontroller by a magnetic field. 10.The method of claim 1 further comprising downloading data collectedduring use and/or charging a battery of the sensor fish via dockingstation.